This invention frelates to a laser treatment apparatus used, for example, in plastic surgery of dermatology, and, more particularly, to laser treatment apparatus which is adapted for the eradication or medical treatment of pigmented naevi consisting of abnormal blood vessels or pigmented cell agglomerations by radiating laser beams having a proper amount of energy onto said agglomerations.
Hitherto, various medical treatments of naevi have been attempted in the fields of surgery, dermatology and radiopathology. Such treatments have included surgical procedures such as excision, suture, skin grafting and surface skin exfoliation. In dermatology pharmacotherapy, dry ice and electrolysis treatment are used. Radiotherapy involves the application of radium, cobalt, strontium, etc. The above-listed processes may be considered the main types of medical treatment. However, these treatments have the drawback that despite the major invasion of the body a satisfactory therapeutic effect cannot be obtained. Moreover, surgical treatment is painful and sometimes requres long hospitalization. Consequently, there is a strong demand for improved treatment.
In recent years, histological research has been conducted to study the origin of the naevi, but progress is slow. Abnormal pigmented cells observed in, for example, the so-called vasuclar naevus are generally less transparent than normal cells, and absorb visible light rays more strongly than the normal transparent cells. Therefore, visible high energy light rays radiated on said abnormal cells are selectively absorbed, and changed into heat energy. As a result the abnormal cells are broker down due to intense burning. Conversely, the normal cells have higher transparency and absorb little of the above-mentioned high energy light rays, resulting in less heat damage. Consequently, the radiation of the aforementioned high energy light rays on the pigmented naevus causes only the abnormal cells to be selectively burnt off. In this case, the more transparent normal cells, perspiratory glands and tissue absorb little light, and are not irreversibly damaged. Therefore, the burnt normal cells and tissue are rapidly healed with only minute cicatrices remaining. Therefore, if it is possible to select such visible light wavelengths whose light energy is absorbed less by the normal cells of the naevus of the diseased spot and is absorbed to a greater extent by the pigmented cells, and if it is possible to set the energy density of said wavelengths at a prescribed level, then the pigmented cells canb e selectively destroyed. Laser beams represent light rays which satisfy the above-mentioned requirements.
At present, various laser medical apparatus have been proposed. FIG. 1 illustrates one such apparatus. Reference numeral 1 denotes an apparatus body. The body 1 comprises a power source 1A, a laser oscillator 1B and an operation panel 1C. Laser beams issue from laser oscillator 1B. They are conducted through an optical fiber 3 and ejected from the distal end of a hand piece 4. Argon laser rays, which have a typical wavelength of 5,140 A, and ruby laser rays, which have a typical wavelength of 6,943 A, provide a relatively large output of a visible light range effective for the treatment of pigmented naevi and are now being used in practical applications. Although ruby laser beams can provide high light energies and a broad radiation area, they have the drawback of being generated by pulse oscillation. This requires a longer overall radiation time, thereby lengthening the treatment period. Conversely, the argon laser beams have the drawback that they provide a lower light output (about several watts) than the ruby laser beams, but have the advantage that they can be better controlled and can be radiated on a relatively small area. Morover, they can be operated and handled at a higher speed and are more adapted for the treatment of a delicate structure.
The above-mentioned laser treatment apparatus is generally used by holding the hand piece 4. While the operator observes the diseased spot, the spot on which the laser beams are to be radiated is progressively shifted by an extent corresponding to the flux of the laser beams radiated from the end of the hand piece 4. The operator carries out treatment by radiating laser beams intermittently or continuously using a pedal switch, for example.
The energy intensity of the laser flux issued from the laser oscillatory progressively decreases from its center to its peripheral portion as seen from FIG. 2. This is called Gauss' distribution. FIG. 2a indicates Gauss' distribution by planar contour lines. FIG. 2b is a three-dimensional view of Gauss' distribution.
When laser beams having different energy intensities are radiated on a patient's diseased spot, radiation irregularities typically arise in accordance with the different energy intensities as shown in FIG. 3a. It is therefore necessary to apply an amount of radiation sufficient to heal the patient's diseased spot without causing ugly cicatrices or scars to be left at the central portion of said diseased spot in which highest laser beams energies tend to concentrate. The results of animal tests and clinical experience are being studied to determine the proper level of laser beam energy. At present, it is possible to determined the type of the patient reaction to laser beams and the extent of the cicatrices remaining according to the magnitude of the laser output and the volume of its flux (that is, the area of laser radiation). Further, it is possible to determine the efficiency of radiant heat and propagated heat by measuring the laser beam radiation time. It is also possible to define the moisture quantity in the case of thermal treatment and the cooling effect of blood by measuring the intervals at which laser beams are radiated.
FIG. 3b illustrates the case where a plurality of linearly arranged laser beam fluxes having a radiation diameter d are emitted under uniform conditions. It has been determined from clinical experience that the desired result can be attained if the pitch p between the respective laser beam fluxes corresponds to 30 to 40% overlap of the radiation diameter d. FIG. 3c shows the condition of a diseased spot which has been subjected to the radiation of laser beams and which has been healed after a certain lapse of time without any marks of cicatrices.
FIG. 4a shows the process of radiating laser beams on a patient's diseased spot. A plurality of laser fluxes are radiated so as to be linearly arranged in a partially superposed fashion "D". Thereafter, a similar group of laser fluxes are radiated near the above-mentioned laser fluxes at an interval d.sub.1, which is smaller than the radiated diameter d of said laser fluxes. This second laser flux-radiated spot is referred to as "D.sub.1 ". Namely, the radiation of laser fluxes is carried out in a zebra pattern. This zebra pattern laser flux-radiating process is deemed the best method, the efficacy of which has been proved by experiments undertaken in regard to the effect of radiated heat and propagated heat and the cooling effect of the blood. FIG. 4b shows the patient's diseased spots which were subjected to the abovementioned zebra pattern laser flux-radiating process and which resulted in the healed conditions D', D.sub.1 ' after the lapse of a certain length of time.
FIG. 5a illustrates laser fluxes applied to the non-radiated intervening section of the zebra pattern laser flux-radiating process of FIG. 4b. FIG. 5b indicates the patient's diseased spots which were healed after a lapse of a certain length of time by the application of the zebra pattern laser flux-radiating process on the intervening spaces shown in FIG. 4a.
An actual medical operation with the above-mentioned laser apparatus is carried out in the following manner. The operator grips hand piece 4, and sets hand piece 4 perpendicular to the surface of the diseased spot. The operator holds hand piece 4 in such a manner that the output end face is at a predescribed distance from the diseased spot. While observing that portion of the diseased spot which is to be subjected to laser beams, the operator linearly moves the hand piece 4 to an extent corresponding to the total length of the plurality of laser fluxes linearly issued from hand piece 4 in succession and in a partially superposed fashion. The medical treatment is performed by continuously or intermittently radiating laser beams by actuating a pedal switch, for example. The reason why hand piece 4 is spaced away from the patient's diseased spot at a certain distance is to prevent the laser beam output from being reduced or the end face of the hand piece fiber from being broken due to the blood or flesh particles scattering from the diseased or applicated spot on said fiber end face during the laser treatment.
However, the surface of the diseased spot and the distal end of hand piece 4 are not generally brought into contact with each other. Therefore, it requires considerable skill to securely hold hand piece 4 perpendicularly to the diseased spot and at a prescribed distance. Further, tremendous difficulties are encountered in uniformly arranging with the naked eye the circles of the radiated laser fluxes (generally having a diameter of about 2 mm) or preserving a prescribed interval between the respective radiation circles of partially superposed laser fluxes arranged in the zebra pattern (i.e., an unradiated interval between the fluxes). If, therefore, the arrangement of the circular radaated laser fluxes is rendered irregular, and the respective radiated laser fluxes are superposed on each other to an excessive extent, the diseased spot may be noticeably destroyed, resulting in cicatrices remaining and harmfully affecting the laser treatment. If the respective groups of the radiated circular laser fluxes are spaced from each other too broadly, the intervening regions will remain untreated. If it is impossible to preserve the prescribed energy density of radiated laser fluxes (a function of the radiation time and the distance between the respective circles of radiated laser fluxes, assumingt that the laser output remains constant), then the respective laser fluxes tend to produce burnt marks. Laser fluxes having a greater energy density than is required for the temperature rise of the abnormal cells of the diseased spot are particularly likely to indiscrimately heat the surrounding non-diseased cells which require no laser treatment and thereby destroy normal cells.
As mentioned above, the conventional laser medical apparatus used in plastic surgery or dermatology has various drawbacks. When applied to practical medical treatment, the practicality of the conventional laser apparatus is reduced if the diseased spot is too broad. If the treatment continues for a long time, the operator will tire and the patient must maintain a certain posture for a long time without moving. Also, considerable difficulties are encountered in carrying out an effective laser treatment and the operator must use great skill.
It is therefore an object of this invention to provide laser apparatus featuring simpler positioning, lower skill requirements for operation, and effectively uniform irradiation.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.